1. Technical Field
The present invention relates to a control device and a control method for a robot and the robot.
2. Related Art
Industrial robots are experiencing heightened demands for increases in speed, functions, accuracy and power savings. In a multi-joint robot manufactured to meet these demands, a reduction in weight for realizing an increase in speed and power savings is generally contrary to an increase in rigidity for realizing an increase in accuracy. As such, both the reduction in weight and the increase in rigidity have been attained through a control technique. For example, JP-A-2011-136395 proposes a method of suppressing the vibration of a robot tip that occurs when the motion of a robot stops. Specifically, JP-A-2011-136395 proposes a method of providing an acceleration sensor at the tip of the robot and adding, on the basis of a detected torsional angular velocity and a detected torsion angle, a compensation amount for eliminating torsion to a control input of a motor which drives links to thereby control vibration. Consequently, an improvement in the position accuracy during stoppage and a reduction in standby time until suppression of the vibration have been attained.
However, the control method (i.e., the damping method) described in JP-A-2011-136395 has a problem in that the vibration that occurs during the motion of the robot cannot be suppressed. Specifically, since the method is based on the premise that the timing for acceleration detection is the time when the motion of the robot stops, for example, the vibration and motion strain that occurs during movement of a robot arm cannot be eliminated. Thus, when an operator causes the robot to perform a function such as painting or welding while moving the robot, the deterioration of the accuracy thereof due to the vibration cannot be suppressed.